The present invention relates to a casing structure of a magnetic disk storage system and, more particularly, to a casing structure of a magnetic disk storage system in which a plurality of magnetic disk drives, sometimes called head disk assemblies, are provided, which casing structure can reduce a temperature rise and can suppress a temperature rise to the minimum even if blast means such as cooling fans are out of order.
In a conventional magnetic disk storage system in which a plurality of magnetic disk drives are provided, as disclosed in Japanese Patent Unexamined Publication No. 62-239394, air passages and blast means, independent from one another, are provided surrounding the magnetic disk drives so as to cool the respective magnetic disk drives separately and individually. In another conventional system, as disclosed in Japanese Patent Unexamined Publication No. 2-266599, top and bottom surfaces of a casing of each magnetic disk drive are opened, and a fan is installed to produce a cooling air flow from the bottom toward the top, in order to cool piled magnetic disk drives successively.
As a measure to deal with troubles of blast means, as disclosed in Japanese Patent Unexamined Publication No. 3-97187, there is a method in which two blast means are provided for each magnetic disk drive so that, when one of the blast means falls into trouble, the other will be operated.
The conventional technique disclosed in Japanese Patent Unexamined Publication No. 62-239394 includes highly effective cooling means. However, the blast means for the magnetic disk drives are separate and independent from one another, and consequently, if one of the blast means is out of order or stopped, the temperature of the magnetic disk drive whose blast means cease is raised. In the conventional technique disclosed in Japanese Patent Unexamined Publication No. 2-266599, the piled magnetic disk drives are cooled successively from the bottom to the top. Therefore, the temperature of cooling air is raised at the downstream side of the flow due to heat exchange with heat generated from the magnetic disk drives. As a result, the higher that the magnetic disk drives are located, the higher the temperatures thereof become. Especially in the case of a disk array system in which the number of vertically piled layers is larger, a temperature difference between upper disk drives and lower ones tends to increase. Thus, concerning these two techniques, it is feared that positioning accuracy of disk drives will be degraded to thereby deteriorate the reliability of the magnetic disk storage system.
In the conventional technique disclosed in Japanese Patent Unexamined Publication No. 3-97187, which is a measure to deal with troubles of the blast means, two blast means are provided for each of a plurality of magnetic disk drives. In consequence, the number of the required blast means is twice as large as that of the magnetic disk drives, thereby enlarging the spaces they occupy and increasing their costs. This method involves other problems. For example, it is necessary to provide a control circuit for switching the blast means when one of the blast means falls into trouble.